The Telecommunications Standards Section of the International Telecommunication Union (ITU-T) develops recommendations to facilitate the interoperation of telecommunication networks. One of these recommendations is referred to as G.991.2, which is herein incoroparated by reference in its entirety. ITU-T Recommendation G.991.2 describes a digital subscriber line (DSL) standard referred to as G.SHDSL (Symmetric High-bit-rate DSL or Single-pair High-speed DSL). SHDSL transceivers, which are able to transmit and receive multiple data types over a single connection, are designed primarily for duplex operation over mixed gauge two-wire twisted metallic pairs. In addition, an optional multi-pair (four-wire or two-pair) operation is supported.
In the multi-pair mode, payload data is interleaved between wire-pairs 1 and 2 as discussed in G.991.2. In short, the multi-pair mode allows a single data stream to be divided up between and transmitted over the wire-pairs thereby increasing transmission bandwidth for that data stream. However, G.991.2 does not currently define an architecture for carrying out the multi-pair mode. Moreover, the data stream data transmitted by one pair invariably arrives at the destination at different times than the data stream data transmitted over the other pair. This is because the pairs that a given stream is transmitted over often have distinct transmission characteristics (e.g., regenerators, wire thickness, temperature, length). Efficiently contending with this transmission delay in reassembling the original data stream at the receiving node is not a trivial task.
What is needed, therefore, are techniques for carrying out multi-pair mode transmission in a DSL system.